1. Field of the Invention
The present invention relates to a magnetic fluid seal to seal an annular gap between two members rotating relative to each other.
2. Description of Related Art
In the past, magnetic fluid seals have been known, which seal an annular gap between two members that rotate relative to each other. As for a magnetic fluid seal, there is an advantage in that friction torque can be extremely decreased, in comparison with a seal composed of a rubber, a resin, or the like. Meanwhile, in the case of a magnetic fluid seal, there is a disadvantage in that a structure for stably holding a magnetic fluid in place between two members rotating relative to each other is difficult in comparison with a solid material such as a rubber, a resin, or the like.
In order to stably hold a magnetic fluid in place, there is a need to stably form a magnetic circuit and to decrease the variation in a region (space) where a magnetic fluid is held. Accordingly, in cases when the two relatively rotating members become eccentric to each other, it has been difficult to stably hold the magnetic fluid in place.